A device for erecting walls and/or ceilings especially for exhibition purposes as at fairs and to be used as exhibition pavilions, free-standing structures, single- or multi- story lobby booths and the like, comprises a support-shaped section, a beam for wall and/or ceiling segments being detachably affixed to approximately cross-sectionally T-shaped webs of the support shape-section and a clamp detachably affixed to the inside of the beam which is hollow. The clamp in the assembly position is associated with the undercut channels defined by the webs of the support shaped-section and tightened by a rotationally driven tightening system against two adjacent webs of the support shaped-section while the clamp is simultaneously affixed inside the beam by the tightening system.
In such devices, short, support shaped-sections as a rule are the central or the corner erection components and determine the angles subtended between the walls or ceilings.
The walls or ceilings are held by beams in the form of hollow shaped-sections engaging the support shaped-section by clamping locks. As a rule the various wall and/or ceiling erections, for instance fair booths, which are to be set up in simple manner, will be regular quadrangular, hexagonal or octagonal constructions.
The German Offenlegungsschrift 37 03 907 discloses a device of the initially cited kind and its object already is a further development of a similar device disclosed in the German patent 29 31 026.
The known clamping-lock design of German patent 29 31 026 does incur a drawback in that two to three revolutions of the tightening system, which is a screw, are required to actuate such a clamping lock. As a result assembly and disassembly times of the wall and ceiling constructions are significantly lengthened. In the case of inexpert (i.e., excessive) actuation of the clamping lock, there is the further danger that the walls of the beam, which as a rule is made of aluminum, shall be unduly stressed by expanded rear ends of the lateral retaining elements, and externally visible pressure spots arise at the support walls.
The German patent 29 31 026 incurs further drawbacks in that on account of the loose central retaining element, accurate positioning of the hollow shaped-section (beam) is substantially hampered, in that the two lateral retaining elements will close on one side so that there take place shifts of the clamping lock and the hollow shaped-section it holds, and in that it is impossible to accurately center the clamping lock inside the hollow shaped-section because this clamping lock is merely held in place by the screw head of the tightening system. Because the two lateral retaining elements of the known clamping lock do not rest automatically, disassembly of the hollow shaped-section from the support shaped-section is made more difficult.
While some of the above shortcomings could be averted by the known clamping lock of the German Offenlegungsschrift 37 03 907, on the other hand the cost involved to do so was prohibitive because of a special design of the clamping lock. Illustratively this known tightening system designed as a cam comprises a metal core clad in an injection-molded plastic. An actuation groove is present in the plastic coating and externally covers each lateral retaining element. The metal core of the known tightening system consists of two integral cylindrical elements however eccentrically offset from each other, one of which constitutes the actuation head in the form of a hexagonal socket and projects from the plastic cladding, the other forming an inner support for the plastic cladding used to hold the tightening system inside the central retaining element and to actuate the lateral retaining elements. Furthermore, the second cylindrical element comprises integral, bilaterally supporting collars extending on both sides of the actuation groove.
The drawback in the German Offenlegungsschrift 37 03 907 that hampers practical application is that on one hand the plastic cladding of the tightening system cannot indefinitely withstand the high forces generated when handling said device and therefore the clamping lock will be unfit for service after short operation because of the wear of the tightening system. The tightening system cannot be made entirely of metal because it is too complex in shape. Again the metal core of the known plastic-clad tightening system can be manufactured only at high cost because of its complex shape.
It should be noted that the term "shaped-section" is used for convenience, and includes all sorts of cross-sections, such as U-sections, T-bars, and the like.